GCSE Physics Magnetism questions by topic

Complete the sentences about magnetism.

1. (a)Like poles … each other.[1]
2. (b)Outside a magnet, field lines run from the … pole to the … pole.[1]
3. (c)A coil of wire carrying a current is called a …[1]
4. (d)Moving a magnet into a coil … a potential difference.[1]

A student uses a small plotting compass and a bar magnet on paper.

1. (a)Describe how the compass can be used to plot the field around the magnet.[2]
2. (b)State what the compass needle shows about the field direction at each point.[1]
3. (c)State what happens if two plotting compasses are placed at the same point.[1]

An electromagnet is used to separate steel cans from aluminium cans on a recycling line.

1. (a)Explain why the steel cans are lifted but the aluminium cans are not.[2]
2. (b)State two ways to make the electromagnet stronger.[2]

Match each device to its physics.

1. (a)A loudspeaker makes sound using the … effect.[1]
2. (b)A moving-coil microphone generates a potential using the … effect.[1]
3. (c)A transformer only works with … current.[1]
4. (d)A step-up transformer makes the voltage … and the current …[1]

A wire carrying a current is held at right angles to a magnetic field.

1. (a)Name the effect that produces a force on the wire.[1]
2. (b)State how the direction of the force can be predicted.[2]
3. (c)State two changes that would reverse the direction of the force.[2]

A wire of length 0.20 m carries a current of 3.0 A perpendicular to a magnetic field of flux density 0.10 T.

1. (a)Write down the equation for the force on the wire.[1]
2. (b)Calculate the force.[3]
3. (c)State the new force if the current doubles.[1]

A student pushes a bar magnet north-pole-first into a coil connected to a sensitive voltmeter.

1. (a)Explain why the voltmeter reads while the magnet is moving.[3]
2. (b)State what the meter reads once the magnet is held still inside the coil.[1]
3. (c)State two changes that would increase the voltmeter reading.[2]

A bicycle dynamo turns as the wheel spins.

1. (a)Explain how the dynamo generates electricity.[3]
2. (b)Explain why the lamp glows brighter when the cyclist pedals faster.[2]

A wire of length 0.30 m carries 1.5 A at right angles to a field and feels a force of 0.045 N. (Higher)

1. (a)Calculate the flux density of the field.[3]
2. (b)The wire is rotated so it lies parallel to the field. State and explain the new force.[2]
3. (c)Calculate the force at the original orientation if the current rises to 4.5 A.[2]

A transformer’s primary coil has 100 turns; its secondary has 1 000. The primary is connected to 230 V AC.

1. (a)Calculate the secondary voltage.[3]
2. (b)State whether this is a step-up or step-down transformer, and the turn-count feature responsible.[2]
3. (c)The primary draws 2.0 A. Assuming the transformer is 100% efficient, calculate the secondary current.[3]

A power station sends 500 kW down cables of total resistance 2.0 Ω. Compare the cable power loss at 250 V versus 50 000 V transmission (current = power ÷ voltage). (Higher, Physics only)

1. (a)Calculate the current at 250 V and the cable loss (I²R).[3]
2. (b)Calculate the current at 50 000 V and the cable loss.[3]
3. (c)State the factor by which the loss has fallen and why this matters for the National Grid.[1]

A 460 W device runs from a charger stepping 230 V down to 12 V; the primary has 460 turns. Assume 100% efficiency. (Higher, Physics only)

1. (a)Calculate the number of secondary turns.[3]
2. (b)Calculate the primary current.[2]
3. (c)Calculate the secondary current, and explain why it is so much larger.[3]